Human-machine interfaces that are used to translate human movements to machine movements are used in myriad industries. For example, some rotary wing and fixed-wing aircraft flight control systems include a human-machine interface in the form of one or more control sticks, pedals, yokes, or other devices. The flight control system, in response to input forces supplied to the interface(s) from the pilot, controls the movements of various aircraft flight control surfaces. No matter the particular end-use system, the human-machine interface preferably includes some type of haptic feedback mechanism back through the interface to the interface operator. These haptic feedback mechanisms may be implemented using active devices, passive devices, or both.
In many applications, such as civilian and military aircraft, the haptic feedback mechanisms are implemented using both active devices and passive devices. The active devices are typically the primary haptic means of providing haptic feedback, while the passive devices are included as a back up in the unlikely event the active devices become unavailable or otherwise inoperable. The active feedback mechanisms may be implemented using redundant force and position sensors. Although these types of haptic feedback mechanisms are generally safe and reliable, they do suffer certain drawbacks. For example, the force sensors that are typically used are relatively high-fidelity force sensors, which increase overall system cost and complexity. Moreover, when redundancy is employed to increase overall system reliability, the increased cost and complexity can be significant.
Hence, there is a need for an active human-machine interface haptic feedback system that exhibits suitable fidelity and/or redundancy, without significantly impacting overall system cost and complexity. The present invention addresses at least this need.